A major challenge of survivable wavelength-division multiplexing (WDM) network design is deciding how much spare capacity there should be and where it should be placed, so that interrupted traffic can be recovered within a very short time. Protection, including link protection and path protection, is the main way to solve this problem and to prevent huge losses. Link protection and dedicated path protection currently dominate this fault recovery field. Both have short recovery time and low resource efficiency. Shared path protection is also resource efficient with acceptable recovery time. More and more industries recognize that shared path protection is the trend and are trying to find good methods to design shared protection paths. This paper proposes a new efficient algorithm-Predetermined Protection Path Design (PPD), which can design maximum sharing protection paths. We describe in detail how PPD works, and compare it with the existing protection algorithms. Simulation results show that PPD can design maximum sharing protection paths and achieve 28% better resource efficiency than dedicated path protection as well as 12% better resource efficiency than the current shared path protection algorithms, with acceptable recovery time. PPD also has good generality, scalability and restorability.