Let \(\lambda _{f}(n)\) be the nth normalized Fourier coefficient of the primitive holomorphic Hecke eigenforms of even integral weight \(k \ge 2\) for the full modular group \(SL(2,\mathbb {Z})\) . In this paper, we investigate the asymptotic formula of the power sum \(\sum _{n \le x} \lambda ^{l}_{f}(n)\) for \(l=2m \ge 6\) and \(\sum _{a^{2}+b^{2}\le x} \lambda ^{l}_{f} (a^{2}+b^{2})\) for \(l=2m \) , and improve on previous error estimates.