The bio-oil products by continuous pyrolysis reactor, which takes place at temperatures in the range of 450-600°C, were to compare the quality of bio-oil extracted from different residual plants were, 1) Oil palm bunch [OPB], 2) Water hyacinth [WHC], and 3) Manila grass [MNG]. The preliminary analyses of three residual plants showed that the liquid yield of bio-oil obtained from OPB was highest (29.55 %) and liquid yield of bio-oil obtained from WHC was lowest (28.3 %)., at 350 rpm., and liquid yield of bio-oil obtained from OPB, WHC and MNG were 55.6, 25.55 and 25.67 %, at 150 rpm., respectively. The results showed that biomass extracted from three residual plants had good qualities because of low moisture content and high fixed carbon. The element contents of three residual plants found that high carbon content. The amount of carbon in the bio-oil obtained from OPB, WHC and MNG were 55.91, 55.57, and 55.03 wt.%., respectively., carbon was relatively high in three residual plants. Hence; In this research are concerns the feeding rate, the control gas flow, the temperatures in reactor and reactor operate for produce the hi quality of bio-oil with three residual plants of resist in Thailand.