Current evidence shows that subcutaneous injection of methotrexate results in more rapid and better absorption, higher blood drug levels and less variable exposure than oral dosing. Among patients with rheumatoid arthritis or psoriasis, subcutaneous methotrexate is more effective than oral methotrexate, and has a lower risk of gastrointestinal complaints. For patients in whom oral methotrexate is proved to be inadequate or intolerant, subcutaneous methotrexate also shows good efficacy. Subcutaneous methotrexate can serve as a treatment option before the use of biological agents, and in this way, large amounts of money can be saved. Subcutaneous methotrexate has good application prospects for clinical practice.