The invention belongs to the field of emergency warning and provides a method of warning on poor contact of a primary loop of power equipment. A temperature sensing sealed packet is provided; the temperature sensing sealed packet is provided with an open seam filled with low melting point melt so that a cavity that is closed at the normal temperature is formed; the cavity is filled with irritant gas; the temperature sensing sealed packet is disposed at the contact of the primary loop; a gas-sensitive probe is disposed inside a substation; if the contact of the primary loop has a temperature higher than the melting temperature of the low melting point metal, the low melting point metal in the open seam melts, and the irritant gas in the temperature sensing sealed packet leaks out; the gas-sensitive probe sends out a signal to remind operators of checking the 'poor contact' fault of primary equipment; heating fault caused by poor contact of the primary equipment is discovered by the non-electric-medium detection method, the 'poor contact' fault of the primary loop equipment is monitored, continuing of the fault is avoided. The method is widely applicable to the field of operation monitoring for substations.