The invention discloses a floating drilling platform used for bridge construction and a construction technology thereof. The floating drilling platform comprises a floating supporting platform, a temporary fixing device used for temporarily fixing the floating supporting platform, and a hoisting system distributed on the floating supporting platform; the floating supporting platform comprises horizontal floating bodies, a horizontal supporting framework and horizontal steel plates, wherein the horizontal floating bodies are formed by assembling a plurality of small floating boxes; lowering through holes used for lowering steel casings are arranged on the horizontal steel plates; and the lowering passages are correspondingly reserved on the horizontal supporting framework and the horizontal floating bodies. The construction technology of the floating drilling platform comprises the steps of: firstly, assembling the floating supporting platform; secondly, shifting the floating supporting platform; thirdly, temporarily fixing the floating supporting platform; fourthly, lowering the steel casings; fifthly, constructing drilling piles; and sixthly, constructing base slabs in water. The floating drilling platform and the construction technology disclosed by the invention have the advantages of reasonable design, convenience for construction, low construction cost, good using effect, and capability of solving the problems of large restriction of geographical conditions, incapability of driving drilling pile foundations, incapability of positioning and inserting-piling the steel casings and the like of the traditional floating platform.