The temperature field of sodium silicate bonded sand heating by microwave energy is measured and analyzed by the related characteristic quentities. The result shows that sodium silicate bonded sand heating by microwave energy has characters such as temperature rising speedy and heating occurring from inside to outside at the same time. The reasons of those characters are discussed by testing and analyzing. The viewpoint that the temperature rising of sodium silicate bonded sand heating by microwave energy is revocable by sodium silicate absorbing microwave energy is proposed. The results of this study are useful on rightly understanding the essentials of the heating by microwave energy for sodium silicate sand and rightly constituting heating technology.