The invention discloses a construction method for gas reservoir water controlling. The construction method includes the steps of injecting gas into a gas reservoir to push invading water from a gas layer to a distal well; preparing gel having delayed cross-linking ability, and atomizing the gel to form gaseous dispersant gel; injecting the gaseous dispersant gel with the gas into the gas reservoir, continuing injecting the gas so that the gel is transferred and dispersed in the gas layer; and shutting in the well. The construction method has the advantages that the gel plugging agent can be atomized to evidently reduce injection pressure and adapt to medium and low seepage gas reservoirs; the atomized gel plugging agent is injected to the front, the gas is injecting later, and deep water plugging via the gel plugging agent can be achieved; water blocking can be unlocked, late water controlling is also available, and validity is prolonged; long-term water controlling is available, with over half year of validity.