Abstract With the continuous development of industry, the problem of water pollution is becoming increasingly serious. Methylene blue (Mb) is an important water pollutant that has a negative impact on ecosystems. Photocatalytic technology has been recognized as an effective and environmentally friendly method for solving water pollution, which has attracted widespread research attention. This study providing a solid experimental and theoretical basis for solving water pollution and has high research value. In this paper, MnTiO 3 with different molar ratios (Mn:Ti = 1:0.9 and 1:1) and different calcination temperatures (800, 900, and 1000 °C) was synthesized by sol–gel method. A systematic study was conducted on the structure, photodegradation performance, and photodegradation mechanism of synthetic materials. Research has shown that when the Mn:Ti ratio is 1:0.9 and the calcination temperature is 1000 °C/2 h, pure MnTiO 3 phase can be obtained. Among them, the MnTi 0.9 O 3 ‐900 °C/2 h sample composed of MnTiO 3 , TiO 2 , and Mn 2 O 3 phases showed the highest photocatalytic degradation efficiency (54.3%) towards Mb. The mechanism of the excellent photocatalytic activity of MnTi 0.9 O 3 ‐900 °C/2 h is due to its narrow bandgap, porous structure, abundant oxygen vacancies, and heterojunction structure, which enhances light absorption and improves electron hole separation efficiency.