The invention discloses a manometric grease for an artillery plastic manograph and a preparation method thereof. The prepared manometric grease comprises the following raw materials, with a total weight of the manometric grease as a reference: 50-90% of vacuum grease, 10-50% of talcum powder, 0-30% of beewax and 0-30% of ceresin, wherein a total percentage of the raw materials is 100%. The manometric grease has functions of passing artillery gas, and preventing leakage of artillery gas and ablation of the manograph by high-temperature gas during a testing process of artillery chamber pressure. Besides, the manometric grease has advantages of good usage performance at -50-60 DEG C, no softening under high temperature, good sealing performance, no hardening under low temperature, good fluidity, more outstanding chemical stability, oxidation stability and anti-erosion ability.