Background/Need Postoperative flap perfusion assessment methods still rely on the evaluation of traditional clinical indicators, which have the disadvantage of being subjective and burdensome. Methodology This study describes a self-designed infrared wireless thermometer for flap blood supply monitoring and evaluates its efficacy in the postoperative monitoring of 40 free flaps. Device Description The device consists of multiple temperature and humidity modules as well as a wireless module, which has the advantages of low cost and continuous remote monitoring. Preliminary results The alarm time of the wireless infrared thermometer was 30.5 ± 3.1 hours, and the clinical observation reported 41.7 ± 13.6 hours. Current status In future studies, the device will be tested on different types of flaps in a porcine model.