Objective To research the accuracy of two ultrasound multiplanar measurement formulas for quantitative pleural effusion volume in patients in the seated upright position.Methods A prospective study was used to collect patients with pleural effusion treated for clinical need of drainage during the February-July, 2023 .Patients went an ultrasound examination in the seated upright position，we used a linear formula and two multiplanar measurement formula（column model，variable column model） to calculate the pleural effusion （Vforecast1、Vforecast2、Vforecast3），then immediately did chest puncture drainage with ultrasound guided，recorded the actual chest drainage as Vreal.Linear-regression analysis was taken between Vforecast and Vreal，The intra-group correlation coefficient (ICC) and Bland-Altman diagram were used to analyze the consistency between Vforecast and Vreal .Results A total of 87 patients with 96 pleural effusion were collected include 9 patients which had bilateral pleural effusion; Vreal was 99.9-799.6 ml, mean value was (532.8 ± 183.2) ml; in the training groupVforecast1、Vforecast2、Vforecast3 were (507.6 ± 158.2), (515.2 ± 170.7), and (508.3 ± 166.9).Linear regression analysis showed that Vforecast1、Vforecast2、Vforecast3 were linearly associated with Vreal (R2=0.697,0.912 and 0.945 respectively).The consistency analysis showed that the ICC of Vforecast1、Vforecast2、Vforecast3 in the training group were 0.833,0.955 and 0.972 respectively, while the ICC of Vforecast1、Vforecast2、Vforecast3 in the validation group were 0.828,0.957 and 0.984 respectively; the Bland-Altman plot analysis showed good agreement between Vforecast and Vreal.Conclusion Ultrasound multiplanar measurements can accurately quantify the pleural effusion volume, and the variable column model has the highest accuracy, followed by the column model，both can be used in clinical practice.