This paper aims to determine the different sources of hydrogen that cause hydrogen embrittlement in ferrous materials. The 316L stainless steel was selected as the research object, and subjected to immersion and electrochemical tests in 1.0M HCl solution. The hardness and tensile strength of the test samples were measured before and after hydrogen embrittlement. The hydrogen, which exists in the form of hydrides, was detected through Xray diffractometry (XRD), while the fracture profile and microstructure of the samples were observed through optical microscopy and scanning electron microscopy (SEM), respectively. The results show that the hydrogen ions diffused into the surface of the steel, forming iron hydrides. In this way, the hardness of the steel was enhanced, and brittle failure occurred under tensile load; the amount of hydrides and the probability of hydrogen embrittlement increase with the immersion time in the acid solution; the sample immersed in 1.0M HCl for one day presented the most prominent hydrogen embrittlement, i.e. the highest hardness and lowest ductility. The research results provide insights into the occurrence of hydrogen embrittlement in ferrous materials.