The invention discloses a network real time kinematic (RTK) instant locating method based on big dipper tri-band wide-lane combination. A network RTK data processing center uses a continuous operational reference system (CORS) to real-timely generate and broadcast a virtual observing value with double difference convection layer and ionized layer delay correction information; a user station uses a three-carrier ambiguity resolution (TCAR) method of carriers, pseudo-range combination and step-by-step resolving to rapidly fix two ultra-wide-lane or wide-lane ambiguities so as to obtain a lowest noise wide-lane ambiguity which corresponds to the observing value and is used for locating resolving, and finally, the wide-lane observing value of the fixed ambiguity and atmosphere delay correction which is obtained through interpolation are utilized to perform real-time kinematic locating resolving. By means of the network RTK instant locating method based on the big dipper tri-band wide-lane combination, single-epoch accurate fixing of the wide-lane ambiguity can be achieved by the network RTK user station, and thereby, instant centimeter-level locating can be achieved.