OICC Press Mathematical Analysis and its Contemporary Applications 7 2 2025 05 26 Lie group analysis of partial differential equation with mixed double fractional derivative 10.30495/maca.2025.2054727.1131 EN Yapeng Shi School of Science, Wuhan University of Science and Technology, Wuhan 430081, Hubei, China Yuqiang Feng School of Science, Wuhan University of Science and Technology, Wuhan 430081, Hubei, China; Hubei Province Key Laboratory of Systems Science in Metallurgical Process, Wuhan 430081, Hubei, China https://orcid.org/0000-0002-1208-0509 Jicheng Yu School of Science, Wuhan University of Science and Technology, Wuhan 430081, Hubei, China https://orcid.org/0000-0001-6125-263X Journal Article 2025 05 26 Recently, the theory of Lie symmetry group has been extended to some time-fractional partial differential equations with the mixed derivative of Riemann-Liouville time-fractional derivative and integer-order x-derivative. This paper is the first to apply the Lie group method to fractional-order partial differential equations with time-space mixed derivatives. It discusses the Lie symmetry of this nonlinear partial differential equation and obtains the exact solutions of the equation.