Factive verbs refer to verbs with the function of presupposing the truth value of its subordinate clause. Previous studies have examined factive verbs with canonical sentences, yet not many of them have investigated these verbs systematically with instances from corpus. Taking “知道(know)”, “认为(think)” and “幻想(fantasize)” as examples, this paper investigated 1464 sentences in the CCL corpus, and systematically described the factuality of factive verbs in the actual corpus. This paper also prposed that the subordinate clause of the non-factive verb “think” is not neutral and the subordinate clause of the counter-factive verb “fantasize” is not always false. Additionally, this paper came up with a variety of factuality influencing factors that have not been put forward by academics yet, such as tense, modal verbs, double negation, rhetorical questions, subjects, descriptive adverbials, etc. Finally, this paper introduced the theory of intersubjectivity and appraisal systems to unify the various factuality influencing factors.