The opening-up issue of Guangdong has entered a new phase with the change of international situation after the financial crisis. For the opening-up strategy in a new stage, it is of significance to quantify the openness degree of Guangdong and its effect on the economy growth in the past. By applying six indexes to quantify the openness degree of Guangdong and empirical study on its effect on the economy, it shows that the openness degree corresponded with the economic growth rate. The current period openness expansion can boost the GDP by 0.04 percent in the next period. Different openness areas has diverse positive impacts on the economic growth. Hence, it is necessary to deepen the openness in each area and therefore deepen the gross openness degree, seeking the new impetus of economic growth for Guangdong.