The invention discloses a self-locking type bidirectional blocking sandblaster composed of a shell, an abrasion resistant sliding sleeve core, a blocking bar and a C-shaped lock ring. The self-lockingtype bidirectional blocking sandblaster is used for layer fracturing of a packer and used in an oil testing pipe column; during fracturing, the main effects of the self-locking type bidirectional blocking sandblaster are that a sliding sleeve is opened, a liquid flow channel is built, and meanwhile, an oil pipe channel in the lower portion of the sliding sleeve is blocked, so that fluids are prevented from entering a fractured layer; and during oil testing, the main effects of the self-locking type bidirectional blocking sandblaster are that fluids on the two sides are isolated, and interlayer interference is prevented. The self-locking type bidirectional blocking sandblaster is simple in structure, convenient to operate and low in cost, and is a novel tool for layer fracturing and oil testing.