The invention provides a follow-up spray cooling structure of a piston of a drilling pump. The follow-up spray cooling structure comprises a piston rod, wherein one end of the piston rod is coaxiallyconnected with the middle pull rod, the other end of the piston rod is coaxially connected with a piston assembly, and the piston assembly can do piston motion in a matched cylinder sleeve; a coolingliquid flow channel is formed in the piston rod, one end of the cooling liquid flow channel is formed in the outer wall of the piston rod, an assembly flow channel is formed in the piston assembly from the outer circumference face inwards, and the other end of the cooling liquid flow channel of the piston rod is communicated with the assembly flow channel. The follow-up spray cooling structure ofthe piston of the drilling pump solves the problem that the cooling efficiency is poor due to a large amount of cooling liquid splashing in an existing cooling structure.