The work aims to improve technology and obtain excellent aluminium alloy coating by studying effects of hot-dip aluminizing temperature and time on coating of 35CrMo steel. Five temperature gradients (700~780 ℃) and five time nodes (90~450 s) were set. The 35CrMo hot-dip aluminium-plated coating was prepared by studying hot-dip aluminizing technology of 35CrMo steel. Microstructure of the coating, composition and constitutes of alloy elements were observed with scanning electron microscope (SEM). Thickness of the coating was measured with microhardness tester. A series of metallurgical reac?tions occurred in the steel matrix and aluminum liquid during the hot dip aluminizing process. The steel coating consisted of alloy layer and pure aluminum layer. After being hot dipped for 180~450 s at 720~760 ℃, the coating featured in high quality, uni?form distribution and suitable thickness, and was free from holes, cracks and leakage. The results of SEM line scanning showed that element composition and relative ratio of aluminum and alloy layer didn’t change as a function of process parameters. Mic?rohardness values could reach over 750HV when dipping duration was 180 s to 450 s. In hot dipping process, temperature and time have significant influence on thickness, microstructure and mechanical properties of the coating, and coating quality can be improved by optimizing the process parameters of hot-dip aluminizing.