NOVELTY - Preparing high concentrated marsh gas from human and animal excreta mixture involves: mixing the human and animal excreta mixture with water; grinding it; then placing the grinded mixture in storage tank (3) to make it still and uniformly; placing the obtained uniformly mixed mixture in a fermentation tank (4); carrying out first fermentation by using yeast, where the pH value of mixture is controlled at 5.5-6.5 in fermentation process; then carried out second fermentation of mixture at pH of 5.5-6.5 and temperature of 30-40 degrees C, and keeping continuously turbulent in fermentation process. An INDEPENDENT CLAIM is included for a device for preparing high concentrated marsh gas comprising a stirring tank (1), grinding tank (2), storage tank (3), first fermentation tank (4) and second fermentation tank (5), where the stirring tank, grinding tank, storage tank, first fermentation tank and second fermentation tank is connected with the upper part of the pipeline (6) that is equipped with a conveying pump (11). The fluid pipeline (10) is connected on the second fermentation tank. The fluid pipeline is equipped with a fluid pump (16). The two ends are connected marsh gas circulating pipeline (7) in the second fermentation tank. The marsh gas circulating pipeline is connected with a first air pump (9), where the marsh gas circulating pipeline is further connected with a super-filter (8).    USE - For preparing high concentrated marsh gas from human and animal excreta mixture (claimed).    ADVANTAGE - The present process provides high concentrated marsh gas containing low impurity; speeds up the whole fermentation process; shortens the marsh gas generation cycle; and can fastly generate the marsh gas.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic diagram of a device for preparing high concentration marsh gas.    Stirring tank (1)    Grinding tank (2)    Storage tank (3)    First fermentation tank (4)    Second fermentation tank (5)    Marsh gas circulating pipeline (7)    Super-filter (8)