This report investigates the impact of ISO 9000 standards on the Chinese service industry, analyzing data from 5717 companies. The study compares ISO-certified and non-certified firms, examining the effects on revenue, profit, return on assets (ROA), and return on sales (ROS). Key findings reveal that ISO-certified companies had significantly higher sales and profit, but lower ROS and ROA compared to non-certified firms. The report also notes a positive correlation between operational profit and ROA, and between ROS and profit. Furthermore, the educational qualification of employees was significantly related to ISO adoption status. The study recommends that non-ISO firms adopt ISO guidelines to improve their performance, and suggests further research to include external factors like GST. The methodology includes descriptive and inferential analyses, such as t-tests, ANOVA, and chi-square tests, to validate the hypotheses.