The invention discloses a directly operated type electric valve. The directly operated type electric valve comprises a valve core component and a lower valve base component, and further comprises an upper valve base component, an upper valve base, a lead screw and a motor rotor, wherein the upper valve base is fixedly connected with a lower valve base of the lower valve base component, and inner cavities of the two are communicated; the rotor coats the upper end of the upper valve base, and is relatively fixed with the axial position of the upper valve base; the upper end of the lead screw penetrates through the upper valve base to be fixedly connected with the rotor, and the lower end is in threaded fit with a nut of the valve core component; and a valve core of the valve core component is driven by the nut to move in the axial direction of the inner cavity of the lower valve base to open or close a valve port formed in the lower valve base. The directly operated type electric valve cancels a gear system, reduces unnecessary transmission, and is low in power loss; and as the rotor is relatively fixed with the axial position of the upper valve base, in the working process, the driving torque of the motor is stable, the size of the motor can be effectively decreased, and the valve body is miniaturized. The invention further discloses an assembly method for assembling the directly operated type electric valve.