Injection molding which is adopted to fabricate transparent plastic panel has merits such as high efficiency and low cost, and is being used widely. However, at the end of injection molding process, product may be affected by uneven shrinkage and as a result, bring defects such as warp to the final part. This can greatly damage its mechanical and optical quality. Injection-compression molding(ICM) can significantly minimize these defects. In the present paper, 3D model and coupled calculation method of flow, temperature and pressure are used to simulate the process of ICM for an irregular geometric transparent plastic panel. This method can not only reconstruct 3D flow front, temperature and pressure field of ICM process in a much more realistic way, but also more fully demonstrate the length of 3D fiber flow line(FFL) and the variation of shrinkage rate and its homogenize process. Due to such improved algorithm, great improvement has been made to accurately calculate the shrinkage rate in depth of the panel and predict its warp data, in comparison to the traditional temperature-volume contraction index method, which has important practical value to guide and design the technological process of ICM.