In this talk I will discuss some problems related to solutions with polynomial growth of the following elliptic system △u = uv2,△v = vu2,u,v>0 in Rn: Using a blowing down analysis,we konw that the solution(after a rescaling)converges(up to a subsequence)to(Φ+,Φ-),the positive and negative part of a homogeneous harmonic polynomial.I will discuss a higher order excess decay estimate and show how to use this estimate to prove the uniqueness of the blowing down limit.