Infrared photo detectors have vast and promising applications in military,industrial and other fields,In this paper,we present a method for improving the performance of an infrared photodetector based on an InSb substance,To achieve good performance at high temperatures,thermal noise and intrusive currents should be reduced,For this purpose,a five-layer hetero structure photodetector based on We introduce n+ InSb / n+ In1-xAlxSb / πInSb / p+ In1-xGaxSb / p+ InSb to improve the thermal performance in the mid-wavelength infrared (MWIR) range,With inserting of two thin layers from InAlSb and InGaSb on both side of the new (π) optical absorber created a barrier in the structure that prevents from entrance of diffusion currents and noise carriers at n+ and p+ regions into the active area,And also by reducing the density of unwanted carriers in the active layer,leads to decrease dark current,which is the main limiting factor for photodetectors’performance based on InSb,Our proposed design reduced 49% dark current,increased 57% resistivity (R0) and increased 39% detectivity at 300K,Simulation of the structure was done using the SILVACO ATLAS software,