The invention relates to a control valve of a central air conditioner, which comprises a valve body and a valve core, wherein the valve core is in sliding fit with the valve body; the inside of the valve body comprises three sealing basal surfaces, a water inlet cavity, a water outlet cavity, a water return cavity and a water discharge cavity are formed in the inner cavity of the valve body, and each cavity is provided with an opening; the valve core is provided with three sealing surfaces; when the control valve is in a first state, the water inlet cavity is communicated with the water discharge cavity; and when the control valve is in a second state, the water inlet cavity is communicated with the water outlet cavity, and the water return cavity is communicated with the water discharge cavity. The control valve provided by the invention realizes the simultaneous opening and closing of a water inlet passage and a water outlet passage in the control valve, and state switching can be rapidly carried out. The invention also relates to the central air conditioner applying the control valve, a set of fan coil system is shared by the refrigerating machine set and the heating machine set of the central air conditioner, thus the production cost of the central air conditioner is greatly lowered.