Objective To review and compare the literatures on studying endoleak via intra-sac pressure (Psac) measurement in order to reveal the characters of all types of endoleak. Methods Measured the intra-sac pressure with miscellaneous pressure transducers in vitro and in vivo endoleak models or patients afflicted with endoleak. Compared the difference of Psac among no endoleak and all types of endoleak. Results Psac＞0 but was obviously lower than Psys in no endoleak. Psac approached Psys in type Ⅰ and type Ⅳ endoleaks. Some researches showed that Psac in type Ⅱ endoleak was higher than that in no endoleak and even approached Psys, however the other researches showed that Psac in type Ⅱ endoleak was lower than that in no endoleak. Conclusion Postoperative Psac dropping greatly eliminated the risk of aneurysm rupture, which symbolized the success of endovascular therapy. Even if the type Ⅰ endoleak of small size might lead to obvious elevation of Psac, which necessitates management. The impairment and management tactics of type Ⅱ endoleak remained equivocal, which required further study.