In this paper, the extraction conditions of ulvan from green seaweed Ulva lactuca by using Ultrasound-assisted method were optimised. Experience was designed Box-behnken model with experient areas as following: temperature (X1: 50–90 °C), time (X2: 20–40, min) and solvent-to-material ratio (X3: 50/1–70/1, v/w), objective function (Y: yield) required to get maximum value. The result showed that ...