The “A+guo(過)+O,” which is composed of the same components with “bi” comparative structure and indicates a comparison, was once lost as “bi” comparative structure became common but is recently gaining more users. Accordingly, this paper examines whether “A+guo+O” could be considered as a comparative sentence with a meaning of comparison, and analyzed why there has been a rapid increase in its use in modern Chinese. The “guo” in the “A+guo+O” has been grammaticalized through the frequent combination with adjective constituents which signify degree and the advent of the numeral classifier which signifies the degree of the compared results. Accordingly, it lost its verbal characteristic of meaning “go through, pass” and was grammaticalized as a preposition, which is a comparative construction. As a result, the “Guo” in the “A+guo+O” form could not be combined or used alone, but could only be used with the object and did not accompany the aspect marker, adverb and complement. Such characteristic corresponds with the characteristics of the preposition in modern Chinese and with the characteristics of the comparative constructions “bi (比),” “xiang (像),” and “buru (不如).” That is, “guo,” which had been used as a verb, has been grammaticalized as a construction grammatically indicating the comparative standards as adjectives and numeral classifiers appeared, and the form such as “subject+adjective+ guo+numeral classifier” became the typical form for the prepositional “guo” phrase. Nevertheless, not all adjectives could be used in the “A+guo+O” form with a comparative meaning. The corpus research conducted in this study showed that adjectives with one or two syllables which can have a measure for comparison and are not strongly subjective emotional adjectives could be used in the “A+guo+O” form. The fact that only adjectives, which could be objectively compared, could be used in the “A+guo+O” form is different from the “bi” phrase which is a comparative construction in modern Chinese. While the form of the “guo” phrase, which means a comparison, has become more complicated as supplementary words and additional words have been added to its basic form, the increase in the usage of the “A+guo+O” type reflects the fact that the forms are currently in change and developing.