In order to solve the problem of poor flatness of the face after manual grinding and polishing of the sheet metallographic specimen, a new type of handheld grinding and polishing fixture was designed. Through analyzing the processing technology of the sheet metallographic specimens, the structural composition plan of the handheld grinding and polishing fixture was formulated.Then the key structures such as the positioning device, clamping device and adjusting device of the fixture were designed. And the geometric deformation and stress distribution of the specimen under the critical clamping force and grinding throwing force were analyzed through the finite element method.Grinding and polishing experiments show that the fixture can control the flatness of the polished surface of the specimen to about 20 μm, which is 75% higher than the flatness of the manual polishing.The above research provides a reference for the design of grinding and polishing or performance test fixtures for thin plates.