Swirl is a key parameter that directly influences the efficiency and exhaust property of diesel engine. And it is usually measured and valued by a steady flow test system in designing and development process. This paper firstly presented the scheme of a highly automatic steady test bench, on which the valve lift and test pressure are all computer-controlled. Then it reviewed the varied measuring and analysis methods, and performed some corresponding experiments on the bench. The experiment results show that even under the same test condition,  the results are different if using different measuring or calculating techniques, which should be noticed in the comparison.