The invention provides a three-valve linkage unloading device for cockpit inflation test. The three-valve linkage unloading device comprises a direct current power supply, a first relay, a normally-closed pneumatic valve, a second relay, a first normally-open pneumatic valve, a first three-way pipe, a second normally-open pneumatic valve and a second three-way pipe, wherein the first relay is connected with the normally-closed pneumatic valve; the second relay is respectively connected with the first normally-open pneumatic valve and the second normally-open pneumatic valve; the direct current power supply respectively supplies power for the first relay and the second relay; an external air storage tank is connected with the normally-closed pneumatic valve through the first three-way pipe; another interface of the first three-way pipe is connected with the first normally-open pneumatic valve; the normally-closed pneumatic valve is connected with the second three-way pipe through an external cockpit; another interface of the second three-way pipe is connected with the second normally-open pneumatic valve; the external air storage tank and the normally-closed pneumatic valve form an inflation channel for the external cockpit; the external air storage tank and the first normally-open pneumatic valve form a first deflation channel; the external cockpit and the second normally-open pneumatic valve form a second deflation channel.