The invention discloses a rapid fixing method and system of fuzziness between GNSS network RTK reference stations. The method comprises steps of S1 resolving a double-difference fuzziness floating point solution between the GNSS network RTK reference stations; S2 constructing a virtual indirect adjustment observation model and a constraint according to the double-difference fuzziness floating point solution; S3 using the virtual indirect adjustment observation model and the constraint as an observation equation and a limiting condition in an accompanied limiting condition indirect adjustment model, establishing an indirect adjustment resolving model of an accompanied limiting condition, and resolving an optimal floating point solution of the double-difference fuzziness; and S4 using a least square reduction related adjustment method to carry out searching calculation on the optimal floating point solution of the double-difference fuzziness, and determining the double-difference fuzziness. According to the invention, enclosed constraints of the fuzziness between the reference stations are fully used; the searching range of the fuzziness floating point solution is reduced; and the fuzziness fixing efficiency is improved.