In order to improve the ROP of lower section under 3000m depth in Yi1 well of Mongolia, hydroefflux hammer rotarypercussion drilling technology was used. According to the characteristics of the formation lithology, the impact power and the frequency were selected by the hammer rig testing to determine the rotarypercussion drilling parameters. The hydroefflux hammer was used in the section of 3675m to 3817m with the cone bit. With the reasonable hydraulic parameters and performance parameters of the hammer, the desired high ROP was achieved. The net drilling time of the hammer was 185h with total footage of 142m; under the conditions of the similar stratum and the bit, the footage of 2 rounds rotarypercussion drilling was 10m more than that of previous 4 rounds rotary drilling, and the ROP was increased by 42%, the rotarypercussion drilling technology became a new technical means for Baiyinchagan area.