The partial volume effects (PVE) make the lesion distorted in PET images, which influences clinical diagnosis. A PVE correction method was set up in this study. According to the principle causing PVE, the relationships between the characteristic profiles of the transversal slice and the image of one dimension lesion were investigated based on a large of simulate experiment results for cylindrical lesions. The PVE correction for two dimension lesion image was simplified to perform with one dimension lesion image. It was named one dimension correction. Then the correction method was evaluated with the phantom study. Results: (1) One dimension correction method: The procedure of PVE correction consisted of three steps and the corrected value of lesion' size and radioactivity concentration were formulated. (2) Results of evaluation with the phantom study: The lesions' sizes and radioactivity concentrations were corrected satisfactorily, and the differences between the corrected and the true values were within 6% and 7% for the lesions larger than the system resolution (FWHM). For the smaller lesion, because of the heavier PVE there were much difference between the uncorrected and the true values of lesion' sizes and radioactivity concentrations, it reached more than 80%; it was reduced to about half after correction. A PVE correction approach for PET images of two dimension lesions, the one dimension correction, was proposed. It was simple and fast, and the correction results were satisfactory.