Consider the integral equationwhere Ω ⊂ R n is a smooth bounded domain. For 1 < α < n, the existence of energy maximizing positive solution in subcritical case 2 < q < 2n n+α , and nonexistence of energy maximizing positive solution in critical case q = 2n n+α are proved in [6]. For α > n, the existence of energy minimizing positive solution in subcritical case 0 < q < 2n n+α , and nonexistence of energy minimizing positive solution in critical case q = 2n n+α are also proved in [4]. Based on these, in this paper, the blowup behaviour of energy maximizing positive solution as q → ( 2n n+α ) + (in the case of 1 < α < n), and the blowup behaviour of energy minimizing positive solution as q → ( 2n n+α ) − (in the case of α > n) are analyzed. We see that for 1 < α < n the blowup behaviour obtained is quite similar to that of the elliptic equation involving subcritical Sobolev exponent. But for α > n, different phenomena appears.