The widespread use of traditional digital hearing aids is limited to a certain extent due to the shortage of professionals, and the cumbersome fitting process required for high-performance hearing aids. Against this background, we propose a strategy scheme of self-fitting based on the gain adjustment for digital hearing aids in this paper. First, the scheme combines a multi-channel wide dynamic range compression algorithm and prescription formula to achieve personalized gain compensation for patients with hearing loss. Second, the proposed problem-based guided gain adjustment scheme is used to realize individualized gain adjustment for hearing loss patients. In the gain adjustment scheme, the daily environment factors of patients are considered, and the historical adjustment parameter groups similar to patients are accurately matched by combining the optimized acoustic discrimination algorithm with the similarity matching algorithm. The experimental simulation shows that the proposed scheme can effectively improve patients’ speech recognition rate, speech intelligibility, and speech quality compared with traditional algorithms from both subjective and objective experiments.