Abstract: Long duration,cooperation and user control are the new properties of engineering database transaction and the tranditional concurrency control mechanisms don’t support them.Here presented is a new concurrency control mechanism which is named nested two phases locking protocol based on order compatibility locking.This protocol is based on nested transaction model,and makes use of order compatibility locking to schedule the design cooperation transaction,so it can support those new properties well.Because this protocol is a variant of two phases locking,it is easy to implement by improving the existing DBMS.