The fuel injection and fuel line pressure characteristics at the nozzle during the injection for biodiesel and its blended fuel with dimethyl ether were studied and the effects of injection conditions and mixing ratio were determined. The results show that the injection rate increase in the initial injection stage and decrease in the injection ending stage both accelerate, the peak injection rate increases, and the fluctuation amplitude of injection rate in the duration period increases with the increase of injection pressure. The first trough of nozzle pressure drops in an increasing extent during the injection and each fluctuation amplitude after the injection becomes larger. The phases of all the peaks except the first advance and the differences get large. The injection pulse width increases, the injection duration extends, the injection end delays, the amplitudes of first trough and each peak almost keep the same, but the phase of each peak delays. With the decrease of biodiesel mixing ratio, the injection timing keeps unchanged, the injection end delays and the injection duration prolongs, and the first trough drops and the first peak becomes smaller. Under the same fuel injection conditions, the order of fuel injection per cycle from high to low is high-proportion biodiesel, pure biodiesel and lowproportion biodiesel.