Abstract: The RNA interference regularity of transformer- 2 (tra- 2 ) gene of oriental river prawn Macrobrachium nipponense was studied in this paper to find the injection sites, dose, interference effects and interference regularity. The optimal injecting sites were chosen from muscle, heart, pericardial cavity and the base of eyestalk. The pericardial cavity was the suitable site for injection due to the lowest mortality rate. For the time-dependent silencing experiment, the dsRNA quantity was calculated as 4 μg dsRNA/g body wt. The results of 1,7,or 14 days by Real- time RT- PCR showed that tra- 2 gene relative mRNA expression was significantly reduced (P <0.05) on the 7th day. Experiments of different dose levels showed that the treatment group which was injected at a dose of 0.4μg/g had no interference effect; the groups with dose of 4 μg/g and 12 μg/g had significant interference effect. Compared to dose of 4 μg/g, the dose of 12 μg/g could have interference effect in a relatively short time and last for a longer time. It indicated that the interference pattern would change as the dose changed. But the lowest expression level of the two groups were 23% and 21% of the normal level, with no significant difference（P>0.05）.