The invention discloses a construction structure of a top crown beam of a foundation pit supporting pile. The construction structure comprises steel truss crown beams, support piles, anchor cables, anchorage devices and base plates, wherein the steel truss crown beams are installed on the tops of the support piles and are vertical to the support piles; the support piles have reinforced concrete structures; the anchor cables are buried in the support piles, and one ends of the anchor cables extend out from the top ends of the support piles; the anchorage devices are connected with the ends, extending out from the support piles, of the anchor cables; the anchorage devices are used for tensioning and locking the anchor cables so as to enable the steel truss crown beams and the support piles to be connected into a whole; the base plates are installed at the top ends of the support piles, and are arranged between the anchorage devices and the support piles. The construction structure of thetop crown beam of the foundation pit supporting pile has the beneficial effects that a steel truss structure is adopted, so that industrialization is promoted to be realized, the number of workers onthe construction site is reduced, and the construction speed is greatly accelerated. Furthermore, the construction structure is simple in structure; a template does not need to be arranged during construction of the crown beam, and concrete does not need to be poured, so that the operation is simple and convenient. The steel truss crown beams can be completely recycled and reused, so that not only is the cost greatly lowered, but energy conservation and environment protection are also realized; therefore, the construction structure is high in practical value.