The aim of this research is to analyze the power produced by a cross flow turbine with the addition of Guide Passage Vane Gate (GG) on the turbine runner. The analysis uses a triangle velocity method. Guide Passage Vane Gate (GG) will direct the water jet coming out of the first-stage blade geared to the second stage. This research uses a triangle velocity method, which consists of tangential velocity (u), relative velocity (w), and absolute velocity (v). Triangle velocity was analyzed at the first and second stage of turbine blade both by using the guide passage vane gate and without using a guide passage gate vane. The triangle velocity depiction begins with a collection of field data, i.e. the turbine rotation data. The turbine rotation without a guide passage vane gate is about 1215 rpm while the turbine rotation by using a guide passage vane gate is 1348 rpm. Lastly, the turbine tangential velocity (u), the turbine relative velocity (w) and the turbine absolute velocity (v) were analyzed to obtain the turbine power. The result showed that the cross flow turbine triangle velocity using a guide passage vane gate, would increase the turbine power about 14024.18 watts or 13.4%. This result suggests that by using a guide passage vane gate, the water jet coming out from the first stage turbine blade has been directed to the turbine second stage and there is no water flow intersection.