Period expenses play an extremely important role in the accounting of enterprises. The three accounting subjects of sales management and finance under period expenses, sales expenses and management expenses, are divided into many branches, and the related expenditures are not only frequent but also very fragmented. Some expenses are not composed of a single factor but of two or more factors, which are directly related. Related to the operation of the enterprise. At present, in the period cost, many private enterprises in our country show many problems, such as unreasonable amount and unreasonable cost structure. Based on the accounting standards and the theory of period expenses, this paper takes Kunming Zizi Food Co., Ltd. as an example to analyze some problems and reasons existing in period expenses of many private enterprises, and puts forward corresponding suggestions to promote the development and progress of enterprises.