The aim of the thesis is to utilize essential theory of heat transfer,to use correlative expressions to calculate average convection heat change coefficient and heating temperature of strip in Jet Preheat Furnace (JPF),make the calculating results accordant with production data,and make the calculation to be used the process of production.The method is to collect:entry temperature and speed of strip,temperature and speed of N_2 - H_2,to analyse heat transfer according to length and thickness of strip,jet hole and mutual position of jet piping in JPF,to analyse heat transfer and built the physical model.In mathematic model, Martin correlative expressions are tried to calculate using the data from production,and are modified in part properly.At the same time,heat boundary condition is analysed with theory of impact jet and production data.The conclusion is obtained that boundary condition is rarely average numerical value of temperature of strip and N_2 - H_2 with impact jet condition,instead of a relation of function of temperature of strip, temperature and speed of N_2- H_2,array of jet holes,diameter of hole,distance between hole and strip,and acquired a calculating expression.In calculation of examples,the thesis collected and calculated 15 kinds of strips.The thickness of strips are 2=0.51~1.41 mm,material DQ - IF、DDQ,EDDQ,SEDDQ and 340DDQ.Main assess numerical value is temperature value after strip is heated with certain speed and within section of time.Maximum error in 9 groups of numerical value in the thesis is 3.36%comparing with production data.The correlative expressions can be used in production to adjust temperature of strip through changing speed and temperature of N_2 - H_2 and speed of strip.The correlative expressions are compiled computer process.The process can be applied in on line control of production by rapid calculating speed. The aim of the thesis is to utilize essential theory of heat transfer, to use correlative expressions to calculate average convection heat change coefficient and heating temperature of strip in Jet Preheat Furnace (JPF), make the calculation results accordant with production data, and make the calculate to be used the process of production the method is to collect: entry temperature and speed of strip, temperature and speed of N_2 - H_2, to analyze heat transfer according to length and thickness of strip, jet hole and mutual position of jet piping in JPF, to analyze heat transfer and built the physical model. mathematic model, Martin correlative expressions were tried to calculate using the data from production, and are modified in part properly. At the same time, heat boundary condition is analyzed with theory of impact jet and production data.The conclusion is obtained that boundary condition is rarely average numerical value of temperature of strip and N2 - H_2 with impact jet condition, in stead of a relation of function of temperature of strip, temperature and speed of N_2-H_2, array of jet holes, diameter of hole, distance between hole and strip, and acquired a calculating expression. calculation of examples, the thesis and investigated 15 kinds of strips. The thickness of strips are 2 = 0.51-1.41 mm, material DQ-IF, DDQ, EDDQ, SEDDQ and 340DDQ.Main evaluated numerical value is temperature value after strip is heated with certain speed and within section of time. Maximum error in 9 groups of numerical value in the thesis is 3.36% comparing with production data. The correlative expressions can be used in production to adjust temperature of strip through changing speed and temperature of N_2 -H_2 and speed of strip. Correlative expressions are compiled computer process. The process can be applied in on line control of production by rapid calculating speed.