Force-directed algorithms are widely used in practice for graph drawing. How to evaluate this type of algorithms has been a challenging issue since their performance largely depends on input parameters and thus is not consistent. In this paper, we first review previous approaches used for evaluation of force-directed algorithms. We then present a case study that compares two force-directed algorithms following a newly proposed evaluation framework. This study evaluates the performance of these algorithms in terms of six commonly applied aesthetic criteria and demonstrates how the framework is used. Advantages of this evaluation framework are discussed.