The invention discloses a turbulence double-system evaporator of a water chilling unit. The evaporator comprises a shell, a copper pipe, a front end cover, a rear end cover and turbulence plates; an exhaust hole is in threaded connection with a sleeve, and the sleeve is further provided with an exhaust valve; the inner wall surface and the outer wall surface of the copper pipe are each a surface with threads; a transverse baffle plate is arranged in the middle of the inner side of the front end cover, the rear end cover is welded to the rear end of the shell, and the rear end cover is formed by welding a cylindrical shell and a part of spherical surface; and each turbulence plate is a segmental circle with the radian exceeding the radian of a semicircle, and as for the arrangement mode, part of turbulence plates are arranged uniformly along the inner part of the shell in a spaced mode. According to the evaporator, all the space of the whole evaporator is occupied by the shell, therefore, a water inlet and a water outlet of water and a medium are pre-arranged on the shell so that a large amount of space can be saved, and the design of a main engine is optimized; and the water inlet,the water outlet, the exhaust hole and a drainage hole each adopt a threaded connection mode, and are convenient to install, moreover, maintenance and repair are easy, and compared with a connectionmode using flanges, the fault rate is lower.