The infrared earth sensor is a pose measuring component located on man-made earth satellite for measuring the attitude deviation between the satellite body and the earth. And the collimating infrared earth simulator is the main demarcating device for testing high orbit satellite infrared earth sensor on the ground. In order to solve the practical problem, it is needed to simulate a variety of earth angles during the earth sensor ground performance test. A multi-track infrared earth simulation technology was studied deeply by using a collimating optical system to simulate the target. A general scheme of simulating variable earth angles was proposed, the optical and mechanical structure design methods of key parts on the simulator such as the germanium lens optical system and the variable earth aperture were illustrated in detail. Aiming at the requirement of detection of earth angles, a method of detecting earth angles was also proposed. A detection device was set up, and the simulated earth angles under different tracks were measured actually. The test results show that the simulation accuracy of each earth angle corresponding to orbit altitude 18 000, 35 786, 42 000 km is better than ±0.05°, which can be fully in line with the calibration requirements of the earth sensor.