A method of redistribution layer routing for 2.5D integrated circuit packages is proposed, which is executed by a computer, the method comprising using the computer to perform the following: performing a MMSIM (modulus-based matrix splitting iteration method) based routing to assign pre-assignment nets to tracks such that total vertical distance from each bump pair to the assigned track is minimized; and performing a MWMCBM (minimum weighted maximum cardinality bipartite matching) based routing for bumps connected to the assigned tracks according to matching result to complete redistribution layer routing for integrated circuit packages.