Abstract: Abstract Tensile tests were conducted on cold-rolled materials with obvious yielding phenomena, and abnormal fluctuations were found in the curve during the uniform plastic deformation stage. Conducted tensile tests on samples of different sizes and analyzed the effect of sample width on the tensile curve. The results show that the ratio of the clamping section width to the parallel section width of the tensile specimen was unreasonable, resulting in abnormal fluctuations in the tensile curve. The samling method of increasing the ratio of the width of the hydraulic fixture clamping section to the paralled section or increased the area of the clamping surface could avoid abnormal fluctuations in the curve.