In the paper, a modified linearization algorithm of indoor localization based on Received Signal Strength (RSS) in wireless sensor networks is proposed. Compared to the original RSS linearization algorithm that linearly approximates the exponential relationship between distance and RSS only using one line with a constant linear slope, the modified linearization algorithm piecewise linearizes the exponential relationship according to the relationship between the mobile point and all anchor nodes in the wireless sensor network. The rootmeansquare error of the modified algorithm is very close to the corresponding Cramer Rao bound (CRB), and the modified algorithm is with good ability in antinoise. For the case that anchor nodes are distributed irregularly, the proposed algorithm has obvious advantages in the performance. Meanwhile, the correctness and effectiveness have been verified by the simulated results.