Khaw Sia was born in China and studied at the Sin Hua Academy in Shanghai. He graduated in 1932. He learned the watercolour technique from Scottish artist Sir William Russell Flint in 1933. He migrated to Penang after a sojourn in Bangkok in 1937, where he painted many Thai scenes. In 1954, Khaw Sia visited Bali, and painted numerous oil and watercolour paintings of Balinese maidens and landscapes. He was an expert on orchids and was a member of the American Orchid Society and had travelled extensively to find new species for his garden and painted many watercolours of orchids.