Abstract: An extension application of plant management information systems was studied with the help of mobile equipment. PDA (personal digital assistant) was applied in plant management, the architecture of plant management information systems was opened up, the business process was improved in plant time-check, checking of maintenance spare part storage and intendance of maintenance, and the data traffic between PDA and PC was achieved. Application results of an example show that using PDA in plant management can effectively expand the application range of plant management information systems.