In order to build up a process-centered software engineering environment using ontologies, we present a methodology to manually construct the following ontologies: an object ontology constructed based on constituent elements to make up objects (products), and a process ontology constructed based on the relationships between inputs and outputs. Afterwards, using the constructed ontologies, the environment generates software process plans good for user queries, with both user interaction and constraints satisfaction by the Generate and Test paradigm. Furthermore, case studies show us that the environment works well in generating software process plans good for a query about the intermediate stage of development, between basic design and detailed design.