How to make full use of the full-area radiant energy of parabolic trough collector (PTC) under a large opening area is a key issue that needs to be considered. For this reason, a new trough free-form solar concentrato (TFFC) is proposed, which uses the form of photovoltaic/photothermal simultaneous collection to expand the PTC concentrator. The opening utilization area of the optical device adopts the traditional trough heat exchanger form on the inner side close to the PTC, and the outer side is based on the edge light transmission principle to design a free-form surface concentrating photovoltaic system, which uses an inclined method to expand the energy receiving area of the solar panel, and obtains a very uniform concentrating energy flow distribution. After that, the line tracing method is used to verify its optical characteristics, and compared with the traditional PTC system to complete the sensitivity analysis of structural parameters and the discussion of error factors. The results obtained are of great significance to the improvement and optimization of the trough solar collector system.