A preliminary classification of primary central nervous system lymphoma (PCNSL) was reported based on the MRI radiographical features. We classified the 90 PCNSL patients based on the T1 contrast-enhanced MRI findings and assessed treatment responses. The goal is to provide some guidelines and additional information for diagnosis and treatment planning. We categorized these patients into four distinctive types of PCNSL according to the T1 findings and observed the treatment response rate, which we found the highest in type Ia. This could potentially facilitate the diagnosis and treatment plan of PCNSL in a routine clinical setting.