In this study, a simple, easy and convenient fluorescent sensing system for detection of vascular endothelial growth factor (VEGF) based on VEGF aptamers, aptamer-complementary fluorescence-labeled probe and streptavidin magnetic beads was developed in only one single tube. The VEGF is the most important biomarker in cancer angiogenesis, and is investigated that serum VEGF level was various according to the different type and course of cancers. Hence, efficient quantification of VEGF is able to improve the accuracy of cancer diagnosis and precision of disease surveillance. In this research, the VEGF aptamer was designed to be able to bind with the VEGF by forming G-quadruplex secondary structures, and then the magnetic beads would capture the none-binding aptamers due to none steric interference, and finally, the fluorescence-labeled probes were hybridized with the aptamers captured by the magnetic beads. Therefore, the fluorescent intensity in the supernatant would specifically reflect the present of VEGF. After an overall optimization, the optimal conditions for detection of VEGF were as followed, KCl, 50 μM; pH 7.0; aptamer, 0.1 μM and magnetic beads, 10 μL (4 μg/μL). The VEGF could be well quantified within a range of 0.2-2.0 ng/ml in plasma, and the calibration curve possessed a good linearity (y = 1.0391x + 0.5471, r = 0.998). The detection limit (LOD) was calculated to be 0.0445 ng/mL according to the formula (LOD = 3.3×σ/S). The specificity of this method was also investigated under the appearance of many other serum proteins, and the data showed the good specificity in this aptasensor-based magnetic sensing system. This strategy provided a simple, sensitive and selective biosensing platform for detection of serum VEGF. Finally, it was expected that this detection technique can be promoted to more clinical applications.