The resistance, internal friction and Young's modulus of a high Tc superconductor-YBa2Cu3O7-δ were measured in-situ at 80 K to 300 K. Two obvious peaks of internal friction were observed near Tc On account of character of the peaks, we suggest that these two peaks are associated with the eletronic relaxation between Cu3+ and Ca2+ The peak and anomalies of Young's modulus observed in the range of 160 K to 280 K may be related to the position adjustment of oxygen vacancies.