A miniaturized all fiber Fabry-Pérot interferometer high temperature sensor is presented and experimental studied.The sensor is made by directly spliced ashort section of capillary tube which has an outer diameter of 125um and an inner diameter of 40um with two conventional single mode fibers.For the firstfusion point,the inner diameter collapses to about 27um in the process of fusion by using SM-SM mode program of the fusion splicer.