The utility model relates to a mixing tank truck shedding mechanism, its including installs the discharge hopper of stirring tank body outlet bottom with set up the silo that drops down in the discharge hopper below, drop down the silo and pass through the support arm and connect on the support frame of the agitator tank body, support arm terminal rotates the pendulum rocking arm of installing horizontal setting and set up the pendulum between the two changes positioning mechanism, the upper portion of dropping down the silo hinges the wherein one end at the pendulum rocking arm, is connected with between the top portion of dropping down the silo and the other end of pendulum rocking arm to be used for adjusting the angular adjustment hydro -cylinder that drops down silo inclination. The utility model has the advantages of simple structure, control conveniently and can nimble location unload the angle.