A dispensing pump mechanism is provided. The pump comprises integrally molded temper-evidence part between a container collar and a spout; said collar has multiple off-centre outlet channel for dispensing one or more products from the container; said collar also comprises an integrated air vent to be blocked and opened by the rotation of the spout. The whole pump can be over-molded one-piece structure with elastic parts as being actuating parts. The pump improves the functions of the pump, such as lower restitution rate, less structural parts, lower cost, water/dust proof, lightweight, easy assembly.