The accurate measurement and feedback of brake cylinder pressure is critical to the accuracy, reliability and availability of brake cylinder pressure control. To address the issues of unmeasurable brake cylinder pressure, as well as a faulty brake cylinder pressure sensor cannot provide accurate feedback value, a brake cylinder pressure observer was modeled. Firstly, the structure and principle of the brake system of railway vehicles were introduced and analyzed. Secondly, a mathematical model of the brake system was established, and the brake cylinder pressure observer based on LO (Luenberger Observer) was designed. Finally, case studies on the test bench were conducted, and the experimental results show that the proposed method enables precise estimation of the brake cylinder pressure via the EP (Electro-pneumatic) valve output chamber pressure and control signals, with a steady-state accuracy within ± 1 kPa. The research results provide a basis for closed-loop feedback control of brake cylinder pressure in the absence of sensing and sensor failure.