In order to ensure safety, heavy cranes and ships are usually used for installation of heavy caissons in un-shielded sea. But the cost control of heavy cranes and ships is difficult because of high fees. Taking the caisson installation of coal wharf and breakwater of Fujian Hongsan Power Station as an example, this paper summarizes the cost control and construction organization of the installation of large caissons using the normal floatable crane under the condition of un-shielded sea, which may serve as reference for similar projects.