A state observer based on the high gain technique is proposed to estimate the fluxes of induction motor (IM), which is a strongly coupled nonlinear system, due to the fact that the traditional methods have low precision, are liable to be affected and use too many machine parameters. The diffeomorphism theory is used to transform the IM system to a class of canonical form. This observer, that need not meet the states observable conditions, has low computational complexity and can achieve arbitrary accuracy by adjusting the gain of the high gain observer (HGO). Moreover, the stability analysis is made for the HGO of the nonlinear canonical form, which results in the ultimately bounded stability of the HGO. Simulation and experiment results show the high observation precision, the feasibility and the effectiveness of the proposed observer.