In the present investigation, an attempt has been made to study the effect of different concentrations of liquid seaweed fertilizer of Ulva lactuca on morphological and biochemical changes of Vigna unguiculata L. was assessed. The liquid seaweed fertilizer of Ulva lactuca is having a higher amount of organic and inorganic elements. The physic-chemical analysis of aqueous extracts is light brown in colour and it was rich in calcium, magnesium, sodium, potassium, chloride, sulphate, copper, phosphorus, nitrate and lead. Different concentration of Seaweed Liquid Fertilizer was used and the morphological parameters like root and shoot length, fresh weight showed a decreasing trend with increase in seaweed liquid fertilizer concentration with compare to control plants. Chlorophyll a, b and total sugars, protein and amino acids were decreased at higher concentrations. The study reverals that lower concentration liquid seaweed fertilizer was beneficial for the overall growth of the crop plant.