To overcome the limitation of traditional meteorological drought indices, which rely on historical climatic probability data of the same period for calculation, this paper establishes a meteorological drought index that can reflect the degree of soil drought but only requires current precipitation and evaporation data. Based on the soil water balance equation and in conjunction with the standard classification of soil drought levels, this study utilizes the relationship between the evaporation intensity of the dry soil surface layer and the water surface, along with soil evaporation calculation methods, to derive the expressions of the critical lines representing various drought levels within the cumulative precipitation-cumulative evaporation coordinate system. The four derived expressions of critical lines correspond to four drought grades, namely, mild drought, moderate drought, severe drought, and extreme drought, respectively. Through a forward daily rolling calculation, the point where the cumulative precipitation and cumulative evaporation coordinates are farthest from their respective critical line is identified as the maximum distance point for that critical line. The drought level is determined by the coordinate point that is located in the highest drought level region and has the maximum distance from the nearest lower critical line. The drought index is then constructed based on the distances from this coordinate point to each critical line. The drought index established in this study reflects the level of soil drought. The drought index calculated using the soil drought level distance index model presented in this paper is compared with soil moisture measurement data and drought disaster records. The results indicate that the variations in the drought index presented in this paper exhibit a high negative correlation with changes in soil moisture and a strong consistency with actual drought impacts. The drought index proposed in this study possesses advantages such as clear physical meaning, convenient calculation, and short response time scale, making it of great significance for practical drought monitoring operations.