The invention provides an odorizing device for city gas. The odorizing device comprises a support. An alarm and a controller are fixed to a cross rod in the middle of the support, and the controller is located on the right side of the alarm. An odorizing agent
barrel is a cylindrical bucket, an end cover sealed through threads is arranged at the top of the odorizing
barrel, and an odorizing agentcan be added into the odorizing agent
barrel after the end cover is opened. A through hole is formed in the right side of the end cover, and the hole is a threaded hole. A one-way valve is in sealed connection with the through hole of the end cover at the top of the odorizing agent barrel through a thread. An odorizing agent
pipe is made from a transparent material, and connected to the right sideof the odorizing agent barrel through an upper
pipe and a lower
pipe, and the odorizing agent pipe communicates with the odorizing agent barrel. Pressure in the odorizing agent pipe is kept consistent with pressure in the odorizing agent barrel, and an odorizing agent at the same liquid level can be obtained. By arranging the one-way valve, when negative pressure in the odorizing agent barrel reaches the pressure value of the one-way valve, external air can enter the odorizing agent barrel to maintain the
internal pressure, so that the pressure value in the odorizing agent barrel is larger than the air pressure value in an air conveying pipe all the time, and it is guaranteed that the
pressure difference exists, and so that the
oxidizing agent enters the air conveying pipe.