The CASCA is a 32-channal readout ASIC designed for the TPC based X-ray Polarimeter. We propose a prototype Readout system of the CASCA chip for the XTP. The system mainly consists of three kinds of modules. The ASIC cards, mounted with CASCA chip, are designed for sampling XTP signals. The Adapter card, edged-mounted with the ASIC card, is in charge of digitizing the output from ASIC card and driving it. The Main Controller card provides 8 channels for 8 Adapter cards based Serial-RapidIO protocol at 6.25Gbps bandwidth, and it transmits data through 10 Gigabit Ethernet, therefore 256 electronics channels are achieved. The readout system can be tailored to specific sizes to adapt to the experiment scales and readout requirements.