The invention discloses a micro-imaging system with a combined optical tweezers function and expanded focal depth. The micro-imaging system comprises a first laser, a first reflector, a first spectroscope, a first lens, a second lens, a first acousto-optic deflector, a third lens, a fourth lens, a fifth lens, a second acousto-optic deflector, a sixth lens, a second spectroscope, a first dichroic mirror, a second dichroic mirror, a first object lens, a sample table, a second object lens, a third dichroic mirror, a third spectroscope, a fourth spectroscope, a fifth spectroscope, a first four-quadrant position detector, a second four-quadrant position detector, a position detector, an LED light source, a first detector, a second laser, a first cylindrical lens, a cylindrical lens group, a fourth dichroic mirror, a scanning galvanometer, a first telescope system, an electric control lens, a second telescope system, a second reflector, a third telescope system, a slit, a third reflector, asecond cylindrical lens, and a second detector. The system utilizes an electric control lens to scan planes with different focal depths and has the advantages of no mechanical vibration and high imaging quality.