The investigation on localized hydrogen distribution and evolution in metal is an important basis for revealing the mechanism of high-pressure hydrogen embrittlement and predicting the service performance of load-bearing components. Due to the difficulty in testing the local hydrogen distribution in materials, various testing and research methods have shortcomings and deficiencies at present. Scanning Kelvin probe force microscopy (SKPFM) was used to study the characteristics of local hydrogen distribution, including high spatial resolution and nondestructive test. However, since many factors affected the test results, the testing methods able to ensure the reliability of results were set up. The influences of key parameters, test temperature and test atmosphere on SKPFM test results were studied. Then, based on above factors and influence laws on SKPFM test results, corresponding control strategy was established and the SKPFM-based method for measuring the local hydrogen distribution on the near surface of metal was improved and verified for effectiveness. Finally, the established method was applied to investigate the evolution of hydrogen distribution in thermally hydrogen-charged S30408 austenitic stainless steel. For a specific drive frequency, there was always an optimal interval of drive phase. In this interval, the error of CPD test was the smallest and the data stability was high. Changes in drive frequency led to changes in the optimal phase interval. Moisture and oxygen in the air not only had a great influence on the overall value of CPD, but also changed the difference of CPD at different positions. According to the observation of the evolution law of hydrogen distribution in S30408 after charging hydrogen at high temperature and high pressure, the results show that the diffusion rate of hydrogen in S30408 varied with the crystal orientation. SKPFM can effectively test the local hydrogen distribution in metal, which provides support for the study of HE mechanism.