Virtual laboratory is computer software that has the ability to perform mathematical modeling of computer equipment presented in the form of simulations. Virtual laboratory is not a substitute for real laboratory, but are used to complement and improve the weaknesses of real laboratory. This study aims to determine the effect of virtual laboratory combination with demonstration methods on lower-secondary school students' scientific literacy ability in a science course. The design of this research is quasi-experimental. The sample in this study was 102 students (12-14 years old) in a lower-secondary school in the city of Yogyakarta, Indonesia, used as experiment 1 group 1 (n = 34), experiment 2 group (n = 34), and control group (n = 34). The three groups (experiment 1, experiment 2, and control) were tested with pretest and posttest. Experiment 1 group used virtual laboratory combination with demonstration methods, experiment 2 group used only virtual laboratory, and the control group used only a demonstration method. Scientific literacy ability was measured using multiple-choice tests before and after treatment. Statistical tests on mixed methods ANOVA were used to determine how effective the use of virtual laboratory combination with demonstration methods was in improving scientific literacy ability. The research result based tests of Within-Subjects Effects showed that there is a difference between the pretest-posttest scores of scientific literacy ability (F = 10.50; p < 0.05) in each group. The results based pairwaise comparison show that the significance value is <0.05, and there is a significant increase in the pretest-posttest scores of scientific literacy ability in every group. The result of effect size (partial eta squared) shows that the experiment 1 group to increase scientific literacy ability is 84.5%; experiment 2 group is 78.5%; control group is 74.3%. So, it can be concluded that experiment 1 group (virtual laboratory combination with demonstration methods) provides the most effective contribution to improving scientific literacy ability when compared to experiment 2 group virtual laboratory only) and control group (demonstration methods only).