Automated writing scoring can not only provide holistic scores but also instant and corrective feedback on L2 learners' writing quality. It has been increasing in use throughout China and internationally. Given the advantages, the past several years has witnessed the emergence and growth of writing evaluation products in China. To the best of our knowledge, no previous studies have touched upon the validity of China's automated essay scoring systems. By drawing on the four major categories of argument for validity framework proposed by Kane--scoring, generalization, extrapolation, and implication, this article aims to evaluate the performance of one of the China's automated essay scoring systems--iWrite against human scores. The results show that iWrite fails to be a valid tool to assess L2 writings and predict human scores. Therefore, iWrite currently should be restricted to nonconsequential uses and cannot be employed as an alternative to or a substitute for human raters.