To enlarge the effective field of view, speed up the response time and reduce the noise of the real-time surface profile measurement of microstructures by traditional dual-wavelength digital holographic microscopy, a technique named dual-wavelength digital microscopic image-plane holography is developed. It is a combination of digital microscopic image-plane holography and the traditional dual-wavelength digital holographic microscopy. The phase and amplitude can be directly extracted from the hologram plane to yield the surface profile of microstructure without calculation of the diffraction after recording the image-plane hologram. A microstep with several micrometers in height is tested by the dual-wavelength digital image-plane holographic microscope, the traditional digital holographic microscope and the stylus profilometer. As can be seen from the comparison of the testing results, the dual-wavelength digital microscopic image-plane holography is feasible with the characteristics of single-exposure, completely full-field, short response time and low noises. It is especially suitable for the real-time surface profile measurement of microstructures with step height in the micrometer range.