The continuous thin plate blank casting and rolling process for producing high strength V-N micro alloy steel belt includes smelting and refining in electric furnace or converter, continuous casting, heating after solidification inside bottom heating furnace, hot rolling, laminated flow cooling and winding. The continuous thin plate blank casting and rolling process has the technological parameters of: furnace entering temperature of cast blank 900-1050 deg c, homogeneous heating temperature 1050-1250 deg c, initially rolling temperature 1000-1170 deg c, finally rolling temperature 840-950 deg c and winding temperature 530-670 deg c. The molten steel contains: C 0.03-0.08 wt%, Si 0.01-0.8 wt%, Mn 0.1-2.0 wt%, V 0.01-0.20 wt%, Al 0.01-0.06 wt% and N 0.002-0.03 wt%. The produced high strength and fine grain steel belt and plate has ferrite grain size smaller than 6.0 micron, yield strength of 420-700 MPa, and excellent toughness, welding performance and forming performance.