Let X = {X t , t ≥ 0; P µ } be a critical superprocess starting from a finite measure µ. Under some conditions, we first prove that lim t→∞ tP µ ( X t = 0) = ν −1 φ 0 , µ , where φ 0 is the eigenfunction corresponding to the first eigenvalue of the infinitesimal generator L of the mean semigroup of X, and ν is a positive constant. Then we show that, for a large class of functions f , conditioning on X t = 0, t −1 f, X t converges in distribution to f, ψ 0 m W , where W is an exponential random variable, and ψ 0 is the eigenfunction corresponding to the first eigenvalue of the dual of L. Finally, if f, ψ 0 m = 0, we prove that, conditioning on X t = 0,) is a normal random variable, and W and G(f ) are independent.