Research carried out by Blasher on the chronology of the Quran shows that, like the other orientalists, Blasher has not taken into account the traditions about the order of revelation. Based on stylistic's indicators, such as length of the verses and chapters, he has classified the chapters of the Quran into four periods: three Meccan periods and one Medinite period. His assumption is that over the course of the prophetic mission, the verses and chapters were lengthened. Naturally, an important question that arises is that what justification and reason did Blasher have for using these criteria in chronology, and basically to what extent is this method scientifically valid and effective? Using a descriptive approach, this study reviewed the factor of length in chronology of the Quran with an emphasis on Blasher’s research; at the end, exceptions were found that questioned the validity of the length index in chronology.