This paper analyzed low emissions on a hydrogen-fueled spark ignition (SI) engine at the cold start period under rich combustion through ignition timing (IT) control. Cold start characteristics of hydrogen-fueled engine were investigated experimentally. The study was performed under different IT. The results demonstrated that when excess air ratio (lambda) was 0.7 and IT varied from 25 degrees CA BTDC to 10 degrees CA ATDC, the peak cylinder pressure of the first cycle and the successful start time (SST) of hydrogen engine first increased and then decreased with the retard of IT. At 15 degrees CA BTDC, the hydrogen engine gained the shortest SST and the highest cylinder pressure in the first cycle. Flame development period (CA0-10) first shortened and then lengthened, and flame propagation period (CA10-90) prolonged when IT gradually retarded. The average NOx emissions efficiently reduced by 90.2%, HC and CO emissions caused by the evaporated lubricant oil reduced individually by 33.8% and 19.7% in the first 6 s during the cold start process with the retard of IT. Especially when IT delayed from 25 degrees CA BTDC to 15 degrees CA BTDC, the effect of IT on HC emissions was significant. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.