In grade 12 mathematics program in Vietnamese secondary schools, students have an opportunity to learn the concept ?integral? and itsapplications. Thus, it helps them to know the practical significance of mathematics in general and calculus in particular. In addition, they also recognize that mathematics is a unified whole, the subjects of mathematics are consistent and mutually supportive. For example, thanks to integration one can find the formulas for calculating the area and volume of shapes that students have learned in Geometry, and can calculate the area and volume of shapes that it is very hard to find by geometrical tools. With such an importance of integral concept, the question is that: what are students? restrictions on theapplication and perception towards concepts ?integral? students? This paper presents some results relating to the above two questions.