This paper describes a novel method of liquid level and density measurement with application in airtight container such as oil storage tank. In order to prove the method, a multifunctional pressure-type liquidometer (MPTL) was designed. The MPTL comprises two pressure sensors for capturing the underwater pressure accurately, by which the MPTL could calculate the density of the liquid and back-calculate the level of the liquid. A digital temperature sensor was implanted in the MPTL to collect the temperature of the liquid. Series of experiments show a favorable linearity of 0.2% and a high accuracy of 0.27%. Besides, the simple fabrication, low cost and unconstrained conditions guarantee its popularity in the petrochemical industry fields. Overall, the findings of this study confirm the feasibility of the novel liquid level measure method and offer an economical scheme for mass producing.