The performance of MEC may be affected by wireless offloading links, the offloading delay is large specifically when the links are week. In this case, the RIS with low cost and hardware complexity can be deployed to build virtual links as so to improve the strength of offloading signal at receiver by adjusting RIS reflection coefficients. However, current studies on RIS-assisted MEC have the following limitations. First, the latency fairness among multiple WDs is not considered; Second, current studies on IRS-assisted MEC systems assume the ideal phase shift model, i.e., each RIS element owns constant magnitude, variable phase shift, and the same response for wideband signals, which will inevitably suffer from serious performance loss in the practical system. Due to the introduction of RIS reflection constraints, the existing RIS reflecting coefficients optimization schemes are no longer suitable for practical IRS-based MEC systems. Third, the communication and computation resources affect each other, so the joint optimization is still difficult.