A numerical study was carried out for a cascade thrust reverser of a turbofan engine with high bypass ratio to investigate the influences of the landing Mach number and crosswind speed on the re-ingestion characteristics of the engine and the flow characteristics with the thrust reverser opened. The results showed that:with the increase of the landing Mach number

the level of re-ingestion of the engine inlet decreased

and then disappeared. The value of the characteristic parameter used to evaluate re-ingestion characteristics reached to an allowable value when the critical landing Mach number was 0.08 without the crosswind. When the thrust reverser encountered the crosswind

crosswind changed the flow direction for the thrust reverser flow. It caused the reverser flow to re-ingest into the engine on the crosswind side with the increase of the total temperature distortion on the air inlet. The value of the re-ingestion parameter increased along with the increases of crosswind speed. Therefore

the critical landing Mach number for the safety increased from 0.08 to 0.12 for the cause of crosswind.