Using the mid-infrared absorption property of methane molecular at 3.31 μm, a portable methane detector is designed and developed. Long-term measurement on the output voltage is performed under the sample gas with volume fraction of 0×10-6 to study the device′s stability. The results show that, because of environmental temperature change, semiconductor electronic components′ parameters, optical components parameters, and methane molecular absorption coefficients all drift. To suppress the effect of temperature change on detection performances, the relationship between the output sensing voltage and ambient temperature is studied experimentally, and voltage shift caused by temperature drift is compensated. Experimental results after temperature compensation show that, the variation range of output sensing voltage can be reduced weekly from 1% to 0.46% under the sample gas with volume fraction of 0×10-6, and the gas volume fraction value can be dropped from 86×10-6 to 37×10-6. The Allan variance of the detection device is also plotted for the sample gas with volume fraction of 3250×10-6. The Allan variance value almost tends to be a constant when the sampling period is longer than 500 s, and the standard deviation value is less than 10×10-6. Therefore, by virtue of temperature compensation, the effect of environmental temperature change can be well eliminated, and the instrument′s stability can thus be improved.