Photocatalytic (PC)-Trombe wall with dual functions of space heating and air purification has a promising way in solar architecture integration. In this paper, a two-dimensional numerical model on air purification and thermal performance of PC-Trombe was established based on relevant experiments in literature. The coupling relations and sequence among the low Reynolds number kappa-epsilon model, Langmuri-Hinshelwood kinetics, natural convection heat transfer and convection-diffusion equations were established and used to solve multiple physical fields coupling. The numerical results were in good agreement with the experimental data in related literature. The effects of environmental factors, geometric structures and operating conditions on the thermal efficiency and formaldehyde degradation rate of PC Trombe wall were investigated. The results show that the thermal efficiency increases with increasing solar radiation and ambient temperature, but it is opposite for inlet temperature of air and ambient wind velocity. However, the thermal efficiency increases first and then decreases as the channel width increases, the maximum thermal efficiency is 52.98% when the width is 0.04 m. For the air purification rate, all factors also show the trend of increasing first and decreasing afterward, there is a maximum air purification rate of 2.91 mu g/s when the channel width is 0.05 m. (C) 2019 Elsevier Ltd. All rights reserved.