Mud volcanoes are geological phenomena characterized by a fluid structure occurring within specific geologic structures and hydrogeological environments and provide valuable information on the ground surface during eruptions. There are numerous mud volcanoes in the North Tianshan area in Xinjiang Province, NW China. The origins of water and gas from mud volcanoes in the Tianquan Area, Baiyanggou in Usu, Aiqigou in Usu, Dushanzi District in Karamay, and Khorgas in Shawan County of the North Tianshan area have been analyzed by investigating isotopic and compositional signatures of them. The water from mud volcanoes in the North Tianshan area may primarily originate from atmospheric precipitation stored in the anticline structure. The stored precipitation, coupled with the arid marine phase and river/lake phase sedimentary sandstones and mudstones (including evaporite rocks, such as rock salt, gypsum and carbonate) experienced a series of complex water–rock interactions and formed the hydrochemical characteristics of the mud volcano water. Through the analysis of the main gas compounds carried out using a gas chromatograph equipped with a thermal conductivity detector, the major component of the gases from the mud volcanoes in the North Tianshan area was determined to be methane, with a range of 85.6–94.6%. In addition, through mass spectrometry analysis, the ¹³C/¹²C ratios of CH₄ and CO₂ were tested. By combining relevant data from other studies, we found that the δ¹³C₁ values of hydrocarbon gases from the North Tianshan mud volcanoes (– 45.8 to – 37.2‰) were consistent with values from oil-associated gases in the Junggar Basin, which indicated that the hydrocarbon gases might be from oil source-rock. The δ¹³\({\text{C}}_{{{\text{CO}}_{{\text{2}}} }}\) values of the mud volcano gases from the North Tianshan area (15.8–20.2‰) are abnormally enriched in ¹³C. This may be due to biochemical actions or the reaction of residual CO₂ and H₂.