Residual smile limits the application of Czerny-Turner plane grating spectrometer in the imaging spectrometer. In this paper, different from the traditional method of smile correction based on prism, a method is proposed, which is based on the tilt field mirror. The field curve is corrected, at the same time, the different wavelength slit images in different regions of the field lens are corrected, and the other optical properties of the system are not changed. The Czerny Turner imaging spectrometer slit is 7.8 millimeter length and 0.016 millimeter wide, spectral range from 0.31 to 0.5 microns, spectral resolution 0.4 nanometers, the object focal length 70 millimeters, 1∶1 magnification. Optimization design results, MTF over 0.8, RMS spot radius less than 9 microns, the relative smile less than 0.2%, meet the design requirements. It shows that the method can be used in the systems with weak signal and low transmittance optical glass.