Low test-taking effort of examinees has been considered a source of construct-irrelevant variance in item response modeling, leading to serious consequences on parameter estimation. This study aims to investigate how non-effortful response (NER) influences the estimation of item and person parameters in item-pool scale linking (IPSL) and whether differential NER for two groups has a different effect on parameter estimation under the equivalent and non-equivalent group designs. Three simulation studies and an empirical study were conducted to answer these research questions. Results show that NER on items in a certain item set (e.g. common new items, exclusive new items) have a dominant negative effect on parameter estimation of items from the same item set, while NER on items from the item pool would seriously impact the accuracy of ability parameters. Discussions and recommendations for item set orders are provided.