Soft erosion strata are often encountered in drilling construction; the cracked and soft rocks usually are eroded by slurry before entering the inner tube or drop out from inner tube because of unstuck core lifter. The low core recovery often results to borehole abandoned. The paper analyzes the causes of low core recovery in soft erosion stratum by an example of bauxite mines in Guizhou, an advanced side spray wire-line coring tool without pump is developed to ensure the core recovery with good effects.