The embodiments of the invention disclose a method and apparatus for monitoring an area. The method comprises the following steps: obtaining a position identification of an area to be monitored; according to a corresponding relation between the position identification and a change threshold, obtaining a change threshold of the area to be monitored; according to preset historical environment data and historical acquisition time of the area to be monitored, calculating a change value of the historical environment data along as time changes, wherein the historical environment data comprises at least one from temperature, humidity, light, cleanliness and smog; and if the change value is greater than the change threshold, sending monitoring signals. According to the method and apparatus for monitoring the area, disclosed by the embodiments of the invention, through comparing the change value of the historical environment data of the area to be monitored as the time changes with the change threshold corresponding to the area to be monitored, whether the monitoring signals are sent out is determined, time and space are combined together, and thus the purposes of performing early warning, inversion and real-time monitoring alarming on the environment of a machine room are realized.