These years,the government and scientific research institutes have proposed policies that encourage scientists in the national scientific research institutes to take secondary jobs outside,in order to promote the transform of scientific productions.

At present,university students having part-time job has become a social trend.

It is rather common for university students to have a part-time job and take part in other social practice activities.

To build a relatively stable team of full-time and part-time teachers,the appropriate policies have to be made by the universities,and colleges(departments).

Employment Contract Law is significant broken is,legislated to stipulate explicitly for the first time part-time job validity,along with the law implementation,non-full-time employing labor form day by day mature,the part-time job will exist massively in our country.

In this paper,we analyse the advantages and disadvantages of concurrent post by establishing a principal-agent model,then give a new model of job-enlargement,and get some results about incentive contract of the enterprise by studying the corresponding effects of the two kinds of incentive mechanism.