This paper presents a novel method which can provide accurate real-time evaluation for Quality of Experience (QoE) of live streaming services. First, we use the modified Analytic Hierarchy Process (AHP) to build a QoE model which is mainly based on video quality and network transmission quality in live streaming services. Then, for video quality, we take into account the unique multi-resolution feature of Internet live streaming videos and design a video quality assessment algorithm mainly based on bitrate, temporal perceptual information (TI) and spatial perceptual information (SI). This algorithm removes the interference of multi-resolution and has a good correlation with subjective perception. And for network transmission quality, we design another assessment algorithm based on buffering time and frequency. Finally, by using the QoE model and the assessment algorithms, we can build a real-time QoE monitoring and evaluation system for live streaming services.