A method of system information transmission for a network in a wireless communication system is disclosed. The method comprises broadcasting essential minimum system information (SI) of a cell of the wireless communication system with fixed scheduled on a downlink broadcast channel, wherein the essential minimum SI includes scheduling information for non-essential minimum SI of at least one of the cell and an auxiliary cell or a frequency location, the non-essential minimum SI is broadcasted with dynamically scheduled on a downlink shared channel, and the scheduling information includes a time and frequency resource configuration and an availability information for indicating whether the cell broadcasts the non-essential minimum SI.