Introduction: Today, the issue of urban solid waste or urban waste is one of the most serious problems in the whole world. Composting plants have a significant amount of time from the production and production stage to the sale and consumption stage. In this study, the effect of compost age on the quality of the compost factory was carried out in Isfahan City waste management organization.
Method: To conduct this study, a compost mass of about 300 tons of newly produced compost and prepared for sale at a particular site from the plant and was done in a special place of four and nine weeks. There are ammonia, nitrate, ammonium, phosphorus, potassium, total nitrogen, mineral nitrogen, organic nitrogen, sodium, calcium, magnesium, carbon, density, EC, pH, oxygen, sulfur, and the ratio of carbon to nitrogen was done at any time with three iterations of the experiment.
Findings: Findings indicate that ammonia, nitrate, ammonium, total nitrogen, mineral nitrogen, EC, pH, moisture, density, and the ration of carbon to nitrogen in the initial compost are respectively as follows: 1800, 58.35, 28.2314, 14000, 2400, 11600, 145.7, 245.7, 85.6, 286, and 54.12. Finally in the 9^th week, they changed as follows: 145.873, 325.81, 61.1122, 63.15065, 63.1215, 13850, 71.5, 35.7, 005.5, 5.279 and 04.22. The amount of ammonia, ammonium phosphor, mineral nitrogen, EC, moisture and density was reduced with a significant difference whereas other factors increased with a significant difference. The results of phosphor were not significantly different. Also, the results of the study revealed that ammonia, ammonium, phosphorus, total nitrogen, nitrogen, EC and COD in the zero weeks were respectively as follows: 244.26, 314.05, 298.73, 1153.6, 325.36, 6289.2, 37.088 and 3635.24, whereas in the ninth week, they changed as follows: 110.36, 141.89, 285.43, 366, 148.98, 217, 728.15, 5733.76. The amount of ammonia, nitrate, ammonium, total nitrogen, mineral nitrogen, organic nitrogen, as well as EC reduced with a significant difference, but the amount of COD increased with a significant difference. The results of phosphor and nitrate were not significantly different. 
Conclusion: Ultimately it can be concluded that the quality of compost is decreased with time lapse and the more it passes after the compost production, the less the food elements in the compost consumed by vegetarians would be.