Abstract: Measurements of liquid level are affected by liquidfluctuation in connected pipe. To address this problem, mathematical model ofliquid flows based on a three-channel connected pipe is set up with theknowledge ofhydromechanics. Mathematic equations of liquid fluctuation in thethree-channel connected pipe are obtained and generated to the case ofmulti-channel connected pipe. With Matlab software,properties of liquid fluctuation in time domain are obtained fordifferent system parameters. Experimental results show that our analysisabout the multi-channel connected pipe is correct.