We present the reconstruction of neutrino flavor ratios at astrophysical sources. For distinguishing the pion source and the muon-damped source to the 3$sigma$ level, the neutrino flux ratios, $Requivphi( u_mu)/(phi( u_e)+phi( u_tau))$ and $Sequivphi( u_e)/phi( u_tau)$, need to be measured in accuracies better than 10%.