Apparatus and methods are provided for on-demand system information (SI) delivery. In one novel aspect, an indicator in the minimum system information (MSI) indicates whether an SI or an SI group is delivered with broadcast or unicast. In one embodiment, the UE receives a MSI, obtains from the MSI the other SI (OSI) delivery mode indicator, and sends an on-demand SI request if the OSI delivery mode indicates the unicast delivery mode, otherwise acquires OSI information in a predefined or scheduled period if the OSI delivery mode indicates the broadcast delivery mode. In one embodiment, the delivery mode is unicast and the SI request is sent at a timing or resource explicitly configured in a SI change notification message. In another embodiment, the delivery mode is broadcast and updated SI is obtained based on the scheduling information included in the SI change notification message.