The invention discloses a side-mounted linkage three-way switching valve. The side-mounted linkage three-way switching valve is characterized by comprising an upper three-way valve, a lower three-way valve and a two-stage turbine operation mechanism, wherein the two-stage turbine operation mechanism is arranged between the upper three-way valve and the lower three-way valve; L-shaped valve cores are arranged inside valve bodies of the upper three-way valve and the lower three-way valve; the two L-shaped valve cores are connected with the two-stage turbine operation mechanism by virtue of an upper valve rod and a lower valve rod. According to the side-mounted linkage three-way switching valve, the L-shaped valve cores adopt full-drift-diameter design, the resistance of lubrication oil is alleviated, so that the pressure is reduced; the liquidity is high; the energy-saving effect is achieved; the valve bodies and end bodies are precisely cast; a sealing ring is low in friction coefficient, long in service life and reliable in sealing property; the L-shaped valve cores are just in contact with a valve seat sealing ring in the rotation process, so that the phenomenon that the valve cores are blocked in the prior art is avoided; the two-stage turbine operation mechanism is convenient to operate; a hand wheel is easy to rotate and low in operation force; due to the design of a turbine worm mechanism, the phenomenon that the hand wheel is blocked and is incapable of rotating can be avoided.