We present results of millimeter line observations toward four nearby gas-rich galaxies(NGC3079,NGC4258,NGC6240,and VIIZW31)with the IRAM 30 meter millimeter telescope.Forty-four lines have been detected in these galaxies at 3mm band and 1mm band.NGC4258shows marginal detections in H13CN(1-0),H13CO+(1-0)and SiO(2-1).However,we didntdetect the isotopic lines of dense gas tracer in NGC3079.We calculated optical depthes of densegas tracers with the detected isotopic lines of HCN(1-0),HCO+(1-0)in NGC4258 andestimated upper limits of non-detected isotopic lines in NGC3079.Simultaneously,Wecompared the intensity ratio of HCN(1-0),HCO+(1-0),HNC(1-0)in the two galaxies.InNGC6240 and VIIZW31,we calculated optical of CN(1-0).We detailly comparedNGC3079 with NGC4258 which are two nearby type II AGN and compared NGC6240 withVIIZW31 which are gas-rich(U)LIRGs.