In this article, the research team systematized the theoretical basis of the monetary transmission mechanism and the impact of interest rate channel in monetary transmission mechanism by Mishkin's approach and used the vector error correction model (VECM) to test the impact of interest rate channel in the monetary transmission mechanism in Vietnam in the period 2005 – 2019. There were 8 endogenous variables included in the VECM model; namely Consumer price index (CPI); Gross domestic product (GDP) at constant 2010 prices (GDPR); Money supply (M2); Refinancing interest rate (ISBV); Average lending interest rate in VND (ILR); Bilateral real exchange rate (ER); Credit to the economy (CRE); VN-Index (VN-INDEX); and, 2 exogenous variables: world consumer price index (PW) and US Federal Reserve interest rate (IFED). The results have shown that: money supply had a clearer effect on average lending interest rate than refinancing rate; Interest rate channel was an important channel to transfer the impact of monetary policy on inflation; Exchange rate and interest rates channel influenced economic growth in Vietnam more strongly than credit and financial asset prices channel did. Besides, the model results also confirm that in Vietnam, inflation in the past played an important role in determining current inflation.