The invention provides a pump body assembly, a fluid machine and heat exchange equipment. The pump body assembly comprises a lower flange, a lower wearing ring, an air cylinder and a piston assembly,wherein the lower wearing ring is positioned in the air cylinder, and the lower flange is positioned below the air cylinder; the piston assembly is arranged in the air cylinder and comprises a pistonsleeve and a piston slidably disposed within the piston sleeve, and the lower end face of the piston sleeve is in limiting fit with the lower wearing ring to prevent radial displacement of the pistonsleeve relative to the lower flange. The pump body assembly effectively solves the problem that a piston sleeve of a pump body assembly in the prior art is prone to generate eccentric rotation and affects the working efficiency of the pump body assembly.