An automatic analyzer of RBC rheological parameters and a microscopic morphological observation technique were employed to investigate the effect of three electric field patterns on erythrocyte sedimentation and aggregation in a physiological saline solution and in autologous plasma, respectively. Experimental results indicate that in a physiological saline solution: 1) Erythrocytes present a lightly aggregation and settle faster by an alternative current electric field; 2) There exists no erythrocyte aggregation by a direct current electric field of constant current and the enhancement of erythrocyte sedimentation is caused only by the action of electric force; 3) Time courses of erythrocyte sedimentation fit well with an exponential type curve by a direct current electric field of constant voltage, and this exponential type sedimentation curve is not caused by erythrocyte aggregation but caused by the decrease of circuit current with time duration. Also shown by experimental results is that the above three electric field patterns all affect the erythrocyte sedimentation in antologous plasma in different contents, which predicts some change in erythrocyte aggregation behavior in autologous plasma by an external electric field.