The interaction between methylene blue(MB) and yeast RNA(yRNA) was studied by the cyclic voltammetry.The interaction was also testified by the UV-visual absorption spectrum.The result indicated that the interaction of MB and yRNA was electrostatic action in the CH3COOH-CH3COONa buffer solution(pH=5.6).And with the increase of the concentration of yRNA,the absorption peak intensity was weaker and weaker.An indirect electroanalytical method for determining yRNA was developed.The minished peak currents of MB were proportional to the concentration of yRNA in the range of 5.0×10-3mg/mL-3.0×10-2mg/mL,and the linear regression coefficient was 0.9976.