The utility model relates to the technical field of engines, in particular to a gasoline engine all-controllable mechanic boost intake system. An intake manifold and an exhaust pipe are fixedly connected to an intake port and an exhaust port in a gasoline engine; a right crankshaft pulley of the gasoline engine is connected with an electromagnetic clutch through a belt; an inlet of the intake manifold is connected with an outlet of an intake master pipe; an inlet of a bypass pipe II is fixedly connected with an outlet of a mechanical booster; an outlet of the bypass pipe II is connected with the intake master pipe; a variable gear ratio device is connected between the mechanical booster and the electromagnetic clutch; an outlet of a bypass pipe I is connected with an inlet of the mechanical booster; an inlet of the bypass pipe I is connected with the intake master pipe; an air filter is fixedly connected to an inlet of the intake master pipe; an intercooler, a check valve and a throttle valve are serially connected between the outlet of the intake master pipe and the inlet thereof. The gasoline engine all-controllable mechanic boost intake system has the advantages that fuel economy of a mechanical boost engine can be improved, the problem that matching gear ratios of the mechanical booster and the engine is difficult is solved, power consumption of the non-electromagnetic clutch mechanical booster bearing low load is decreased, and the mechanical booster can be smoothly and stably switched in and out.