A suspension system of a biaxial optical actuator is provided, including a circuit-carrying base and an oscillation member, which is provided, in a center thereof, with an optical lens. An elastic suspension plate is coupled to the oscillation member and has four corners each forming an elastic unit that projects outside the oscillation member. The elastic units collaborate with support posts to support the elastic suspension plate and the oscillation member at a location above the base. The oscillation member is provided, on each of four sides thereof, with a magnetic device. The four magnetic devices is sequentially activated to apply a magnetic force such that the oscillation member together with the optical lens carried thereon to rotate about two imaginary axes of the elastic suspension plate respectively defined between each pair of two opposite magnetic devices to thereby serve as a rotation axes of the oscillation member.