A design method for a steel structure platform and a trestle structure for shallow water area pole and tower foundation construction is characterized by comprising the following steps that materials used for a steel structure trestle and a platform structure are determined; according to the requirement of a material transport channel, the width of the trestle is determined, and the length of the trestle is determined through the distance between the specific tower position and the shore side, the comprehensive transportation conditions and the construction difficulty; the peripheral size of the steel structure platform is comprehensively determined; the design load of the trestle and the platform is determined; the structural calculation assumption is defined, and the structural design service life is regulated; the platform and trestle structure mechanical analysis is conducted; the application range of the steel structure trestle and the platform is determined, the steel structure trestle platform and the platform structure are universally applied to water surface construction projects, and the application range of the designed trestle and the designed platform structure is determined; and the requirements for the arrangement type and construction of the trestle and the platform are standardized, and actual construction operation is facilitated. The design method can effectively solve the problems that the earthwork volume of traditional soil and stone temporary road building and cofferdam island constructing construction is huge, the surrounding environment is prone to damage, the compensation difficulty of water area culture is large, the traditional cofferdam island constructing construction period is long, and a cofferdam dam body is prone to being affected by a water body.