Dissolution behavior of complex carbonitrides in a Nb-Ti-V microalloyed steel was quantitatively examined by electrical resistivity, transmission electron microscopy (TEM), and optical microscopy. The electrical resistivity increased with solution treatment temperature up to $1250^{circ}C$ for a holding time of 15 min. But, an increasing rate of electrical resistivity with temperature was obviously decreased above $1150^{circ}C$. As the solution treatment temperature increases, irregular shaped Nb-rich carbonitrides disappear and cuboidal Ti-rich carbonitrides are observed. Abnormal grain growth occurs above $1250^{circ}C$ for a holding time of 15 min. The optimal solution treatment temperature of a Nb-Ti-V microalloyed steel was determined as $1200^{circ}C$ for a holding time of 15 min.