A lens module comprises an optical lens component having an optical axis, an image sensing component located adjacent the optical lens component, and a dust trap located between the optical lens component and the image sensing component. The optical lens component has with a lens mount and a lens barrel mounted in the lens mount by way of a threaded connection. The dust trap comprises body having a groove which locates behind the connection between the lens mount and the lens barrel, for receiving dust dropping from the connection, and an inner extension arm separating the groove from the image sensing component for preventing the dust in the groove from moving onto the image sensing component which could reduce the quality of the image.