An important branch of the three-generation infrared focal plane is high operating temperature （HOT） infrared detector. For HgCdTe n-on-p detectors， dark current can be suppressed with n⁺-n^--p structure and good passivation， and then better performance of the detector will be obtained under high operating temperature. Based on the junction formation simulator， the junction formation parameters of HOT device are achieved and combined with the manufacture technology of optimized passivation layer， HgCdTe n-on-p infrared focal plane arrays which can operate at higher temperature was made in Shanghai Institute of Technical Physics（SITP）. The performance of HgCdTe n-on-p infrared focal plane arrays was studied at high operating temperature. One of mid-infrared detector has reached good performance under different operating temperature. The NETD is 6.10mK and operability is 99.96% at 80K， and the NETD is 11.0mK and operability is 99.50% at 150K ， which reached the theoretical limit.