An apparatus for simultaneously inspecting adjacent surfaces defects of thermoelectric cooler (TEC) components based on polarization beam splitting imaging is proposed. The optical design of the apparatus for simultaneously inspecting adjacent surface defects of TEC components is discussed. The proposed apparatus employs polarization beam splitter and polarization camera and meets the conditions of equal-optical-path imaging for both top and side surfaces. The experimental investigations on defects inspection with equal-optical-path polarization imaging system are conducted. The results indicate that the proposed inspection technique with polarization splitting equal-optical-path imaging is capable of simultaneously inspecting the adjacent surfaces defects and the optical apparatus can well meet the performance requirements for inspecting adjacent surfaces defect of TEC components. The inspection resolution can reach 110 lp/mm when equal-optical-path confocal imaging is met, but the inspection resolution reduces to below 45 lp/mm when the defocus is around ±0.20mm. It was noted that the developed technique has obvious advantages of rather good imaging quality, easy adjustment of imaging system, simplified and reliable optical configurations , and improved defect inspection performance.