Aiming at the coordinated planning problem of energy production and hydrogen demand in the electricity-hydrogen-transportation coupled network, this paper focuses on the capacity configuration and equipment siting of hydrogen energy storage facilities as well as wind-solar farms, and proposes a siting and sizing method for green hydrogen production systems based on the improved information gap decision theory (IM-IGDT). First, a full-process model covering hydrogen production, storage and transportation applications, including the interaction of green electricity, electrical storage and power grid, is constructed to achieve accurate simulation of multi-energy conversion and dynamic supply-demand matching. Second, in view of the uncertainty of wind-solar power output and the randomness of transportation hydrogen demand, an IM-IGDT integrated with entropy weight method and non-dominated sorting genetic algorithm II (NSGA-II) is introduced, and a risk aversion-opportunity capture planning model is established to balance the minimization of hydrogen production cost and the security of power grid operation. Finally, a case study based on the IEEE 33-bus distribution network coupled with a 30-node transportation network is conducted. The experimental results verify the effectiveness of the proposed method, with the levelized cost of hydrogen (LCOH) reduced by 5.3%.