The microscope is one of the classical optical instruments with long development history. Its performance continues to increase, but the microscopic objective short working distance largely limits its application. As the market demand for long distance microscope, its development has important significance. According to the design requirements, determine objective structure firstly, and then use ZEMAX for design and optimization. A working distance of 150 mm, line 0.8, 5 times of magnification, resolution of 6 μm reflecting and catadioptric microscope objective design results are given. The advantages and disadvantages of the two results are compared.