The invention relates to a motor-driven dynamic seat driven by crank connecting rod mechanisms and a motion original point determination method thereof. The motor-driven dynamic seat comprises a seat platform, a base platform and the crank connecting rod mechanisms with deceleration functions, the crank connecting rod mechanisms with the deceleration functions are arranged between the seat platform and the base platform, each crank connecting rod mechanism comprises a machine seat, a crank, a support connecting rod and a reduction box, the reduction box is fixed on the machine seat, one end of the support connecting rod is connected with the seat platform through a universal coupler, the other end of the support connecting rod is connected with the crank through a connecting rod, and the crank drives the seat platform to vertically move. The motor-driven dynamic seat is simple in structure, high in rigidity, strong in anti-impacting force, ultra-long in service life, low in operation noise, energy-saving, clean and simple in operation and maintenance. A user only needs to periodically inject grease for lubricating under a complicated environment, no quick-wear part needs maintaining and changing, and a large quantity of components and after-sale service cost are reduced compared with the prior art.