The invention provides a device and method for improving optical fiber screening strength and coating concentricity. The device comprises a fiber drawing furnace, a main driving wheel, a position measuring instrument, an automatic adjusting device and a PLC (programmable logic controller), wherein the position measuring instrument is close to a lower opening of the fiber drawing furnace and is used for measuring positional deviation of bare fiber; a coating mold is installed on the automatic adjusting device; the PLC is connected with the automatic adjusting device and used for calculating directions and values of the coating mold for position deviation and angle deflection and controlling the automatic adjusting device to drive the horizontal movement and angle deflection of the coating mold; the centers of the fiber drawing furnace, the position measuring instrument and the coating mold are on the same vertical line which is tangent to the main driving wheel. According to the device and method, positions or angles of the coating mold can be adjusted on line to enable bare fiber to pass through the center of a hole of the coating mold under any condition so as to reduce the possibility that the bare fiber is scratched by an upper mold opening, therefore, screening strength scrapping of optical fiber is optimized, and meanwhile the coating concentricity of optical fiber is increased.