The invention relates to a flatly-cutting type plate-casting machine, and particularly relates to lead-alloy plate grid casting forming equipment in manufacturing for a lead-acid accumulator. The flatly-cutting type plate-casting machine comprises an assembly line device which is formed by sequentially jointing a high lead-melting furnace, a tandem-type lead valve device, a lead scoop lead-pouring mechanism, a die opening-closing mechanism, a shaping-conveying mechanism, a plate grid horizontal locating mechanism, a flatly-cutting type cutter die, a plate grid levelling mechanism, a plate grid sheet-receiving mechanism and a circulating water tank, wherein the device performs coordination work under automatic electric control. According to the invention, the plate grid levelling mechanism is adopted, and lead-alloy plate grids enter in the plate grid levelling mechanism to be levelled and compacted, thus realizing automatic casting and compacting forming for the lead-alloy plate grids, finishing a breakthrough of the production flow from nothing, greatly reducing the production intensity and the cost of manual operation, guaranteeing the casting quality of the lead-alloy plate grids, increasing the pass percent of the lead-alloy plate grids, and prolonging the service life of the accumulator.