Continuous renal replacement therapy (CRRT) is a recommended dialysis modality for hemodynamic unstable and critically ill patients with severe renal failure. This study aimed to evaluate changes in serum phosphate levels according to the dialysate used during CRRT and to determine whether the choice of dialysate solutions with different electrolyte compositions in prognosis and mortality. We retrospectively analyzed 117 patients treated with intensive CRRT, including 70 and 47 patients who underwent CRRT with Phoxilium® and MultiBic®, respectively. By independent-samples t test, serum calcium, bicarbonate, and phosphate levels after CRRT for 72h were significantly different between the Phoxilium and non-Phoxilium groups (P < 0.05). The Kaplan–Meier analysis revealed no significant difference in survival between the two groups, demonstrating that the difference in serum phosphate level after 72h of CRRT did not have a significant effect on survival (P = 0.581). The difference in serum phosphate levels after 72h of CRRT might affect respiratory muscles; however, although cumulative survival exhibited a stepwise decrease with longer mechanical ventilation duration, the two groups did not show significant difference in survival (P = 0.819). The incidence of hypophosphatemia was significantly lower in the group where CRRT was performed with Phoxilium dialysate containing phosphate compared to the group where CRRT was performed with non-Phoxilium dialysate, and severe hypophosphatemia did not occur. There were no significant associations between hypophosphatemia, mortality, and duration of mechanical ventilation. Selecting Phoxilium as a dialysate for CRRT should be considered to correct severe hypophosphatemia, prevent complications, and improve prognosis.